MQTT Scope
Auto-subscribed topic tree
Connect and the tree fills itself. Every topic level shows live message and topic counts, and changed topics flash. It stays smooth with tens of thousands of topics. Filter by text or MQTT wildcard, even inside payloads.
See everything on your MQTT broker.
Free MQTT client for Linux, Windows and macOS
A desktop MQTT client for busy brokers: every topic in a live tree, large JSON messages you can actually read, live plots of any value, and a publisher that remembers the messages you send most.
Built for brokers with real traffic
Read large messages comfortably
A collapsible JSON tree that highlights what changed since the last message, syntax-highlighted text, raw and hex views, history, and a Held mode that stops the view from jumping while you read. Search filters a multi-megabyte document down to the matching branches.
See exactly what changed
A structural diff lists every added, removed and changed field between two messages, path by path.
Plot any value, live
Pick numbers from any topic or JSON field, from several topics at once, and organise plots in named tabs. Plots fill the window and move like panels: drag one by its title to put it beside or below another, drag the gaps to resize, pop a plot out to another screen or show it full screen. Drag across a plot to zoom into a time range; Reset view takes you back to live.
Follow state transitions
Switch a plot to States and every signal becomes a labelled lane that changes colour when its value changes, with the value written in. Safety signals, modes and flags read at a glance; vertical lines at timestamps and a time bar synced across plots show what happened when.
Publish safely, again and again
Save the messages you send most and fire them with one click. The publish target never silently follows your clicks once you have edited a message, retained publishes ask first, and double clicks never send twice.
- Every transport TCP, TLS with client certificates, WebSocket; MQTT 3.1.1 and 5.0.
- Several brokers One connection per window; saved connections and messages are shared.
- Live subscriptions Add or remove topic filters without reconnecting.
- Exact numbers 64-bit ids and nanosecond timestamps are shown and re-sent exactly.
- Your shortcuts Every keyboard shortcut can be changed; Enter connects to the selected broker.
- Secure by default Sandboxed UI, payloads never executed, passwords in the OS keychain.
- Hold and reload Space holds the message (or freezes the plots); Ctrl+R starts the timeline over without disconnecting.
- Shareable plot tabs Export a tab of plots to a file and import it on another machine.
- Light on resources Plotting costs microseconds per message; 100,000-point histories redraw in a few milliseconds.
Questions
Is MQTT Scope free?
Yes. MQTT Scope is free and open source under the MIT license, for Linux, Windows and macOS.
Is MQTT Scope an alternative to MQTT Explorer?
Yes. Like MQTT Explorer it subscribes to everything and shows the broker as a live topic tree. It adds a large-message inspector with a structural diff, live plots and state transitions of any JSON field, a library of saved messages, several brokers at once (one per window) and safety guards for publishing to live systems.
Which MQTT versions and transports does it support?
MQTT 3.1.1 and MQTT 5.0 over TCP (mqtt://), TLS (mqtts://, with custom CA and client certificates), WebSocket (ws://) and secure WebSocket (wss://), with username and password authentication.
Can it handle large JSON messages and busy brokers?
Yes. Multi-megabyte JSON messages open instantly because the tree renders on demand, search filters a large document down to the matching branches, and the virtualised topic tree stays smooth with tens of thousands of topics.
Can I plot MQTT values?
Yes. Pick numbers from any topic or JSON field, from several topics at once, and give each series an alias and a colour. Show true/false and status values as state transitions, organise plots in named tabs, drag and resize them like panels, zoom into any time range, pop a plot out to another screen, and export the data as CSV.
Does it work with VDA5050 and robot fleets?
Yes. It was built against VDA5050 robot brokers: state, visualization, order and factsheet messages, 64-bit ids kept exact, and saved instant actions you can send with one click.
How do I install it on Linux?
Download the AppImage or tar.gz from the latest release. On Arch Linux, build the mqtt-scope-bin package from the repository's packaging/aur folder with makepkg -si.
Download
Linux
AppImage tar.gzArch: build the mqtt-scope-bin package with makepkg -si from packaging/aur. The AppImage needs FUSE 2.
macOS
Apple silicon (.dmg) .zipNot notarised yet: right-click the app and choose Open the first time.